System and Method For Testing a Data Packet Signal Transceiver

ABSTRACT

System and method for testing transmission and reception performance of a data packet signal transceiver device under test (DUT). Data packet signals transmitted by a tester with a tester transmit output power (TTOP) contain trigger frames that include data corresponding to a reported tester transmit power (RTTP) of the data packet signals, and a desired received signal strength (TRSS) of DUT data packet signals to be received by the tester. Based on received signal strength of the tester data packet signals reported by the DUT (DRSS), responsive DUT data packet signals having a DUT transmit output power of RTTP-DRSS+TRSS. Successive repetitions of such tester and DUT data packet signals for multiple combinations of values of the TTOP, RTTP and DRSS enable testing transmission and reception performance of the DUT, including determining minimum and maximum DUT transmission power levels, with minimal signal interactions between tester and DUT.

BACKGROUND

The present invention relates to testing a data packet signaltransceiver device under test (DUT), and in particular, testingtransmission and/or reception performance of a DUT with minimal requiredsignal interactions between a tester and the DUT.

Many of today's electronic devices use wireless signal technologies forboth connectivity and communications purposes. Because wireless devicestransmit and receive electromagnetic energy, and because two or morewireless devices have the potential of interfering with the operationsof one another by virtue of their signal frequencies and power spectraldensities, these devices and their wireless signal technologies mustadhere to various wireless signal technology standard specifications.

When designing such wireless devices, engineers take extra care toensure that such devices will meet or exceed each of their includedwireless signal technology prescribed standard-based specifications.Furthermore, when these devices are later being manufactured inquantity, they are tested to ensure that manufacturing defects will notcause improper operation, including their adherence to the includedwireless signal technology standard-based specifications.

Testing of such wireless devices typically involves testing of thereceiving and transmitting subsystems of the device under test (DUT).The testing system will send a prescribed sequence of test data packetsignals to a DUT, e.g., using different frequencies, power levels,and/or signal modulation techniques to determine if the DUT receivingsubsystem is operating properly. Similarly, the DUT will send test datapacket signals at a variety of frequencies, power levels, and/ormodulation techniques for reception and processing by the testing systemto determine if the DUT transmitting subsystem is operating properly.

For testing these devices following their manufacture and assembly,current wireless device test systems typically employ testing systemshaving various subsystems for providing test signals to each deviceunder test (DUT) and analyzing signals received from each DUT. Somesystems (often referred to as “testers”) include, at least, one or moresources of test signals (e.g., in the form of a vector signal generator,or “VSG”) for providing the source signals to be transmitted to the DUT,and one or more receivers (e.g., in the form of a vector signalanalyzer, or “VSA”) for analyzing signals produced by the DUT. Theproduction of test signals by the VSG and signal analysis performed bythe VSA are generally programmable (e.g., through use of an internalprogrammable controller or an external programmable controller such as apersonal computer) so as to allow each to be used for testing a varietyof devices for adherence to a variety of wireless signal technologystandards with differing frequency ranges, bandwidths and signalmodulation characteristics.

A recent wireless local area network (WLAN) standard in the IEEE 802.11set of specifications, known as IEEE 802.11ax, operates in existing 2.4GHz and 5 GHz spectrums and will incorporate additional bands between 1and 7 GHz as they become available. In addition to using MIMO andMU-MIMO, OFDMA has been introduced to improve overall spectralefficiency, and higher order 1024-QAM modulation support for increasedthroughput. Though the nominal data rate is just 37% higher than IEEE802.11ac, it is expected to achieve a 4× increase to average userthroughput due to more efficient spectrum utilization and improvementsfor dense deployments. However, requirements for 802.11ax poweraccuracies of transmit (TX) power and received signal strength indicator(RSSI) readings of a device are significantly more restrictive to ensureits compatibility with and operations within a WLAN.

Accordingly, TX power and RSSI must be calibrated and tested as part ofthe manufacturing process. While TX power testing may generally besimple and optimized for efficiency with technologies like MPS (multipacket testing), RSSI testing typically requires querying the DUT forits measured or reported RSSI value. However, querying the DUT isinefficient due to the additional test time needed to accommodateexchanges of query and reply packets.

Additionally, development software for manufacturing testing issignificantly complicated by the fact that DUT calibration is oftenimplemented differently among the chipset manufacturers as well as fromchipset to chipset by a manufacturer. For example, as noted, calibrationof receive (RX) signal operations is often particularly time consumingdue to the need for querying the DUT for its receiver operation statusand/or performance.

SUMMARY

A system and method are provided for testing transmission and receptionperformance of a data packet signal transceiver device under test (DUT).Data packet signals transmitted by a tester with a tester transmitoutput power (TTOP) contain trigger frames that include datacorresponding to a reported tester transmit power (RTTP) of the datapacket signals, and a desired received signal strength (TRSS) of DUTdata packet signals to be received by the tester. Based on receivedsignal strength of the tester data packet signals reported by the DUT(DRSS), responsive DUT data packet signals having a DUT transmit outputpower of RTTP-DRSS+TRSS. Successive repetitions of such tester and DUTdata packet signals for multiple combinations of values of the TTOP,RTTP and DRSS enable testing transmission and reception performance ofthe DUT, including determining minimum and maximum DUT transmissionpower levels, with minimal signal interactions between tester and DUT.

In accordance with exemplary embodiments, a method of testingtransmission and reception performance of a data packet signaltransceiver device under test (DUT) includes: transmitting, with atester for a DUT, a tester data packet signal including a trigger frameand having a tester transmit output power (TTOP), wherein the triggerframe includes data corresponding to a reported tester transmit power(RTTP) of the tester data packet signal, wherein the RTTP and TTOP areunequal, and a desired received signal strength (TRSS) of a DUT datapacket signal to be received by the tester from the DUT; receiving, withthe tester from the DUT, a DUT data packet signal having a DUT transmitoutput power of RTTP-DRSS+TRSS, wherein DRSS is a received signalstrength of the tester data packet signal reported by the DUT; andrepeating the transmitting and the receiving for a plurality ofcombinations of values of the TTOP, the RTTP and the DRSS.

In accordance with further exemplary embodiments, a method of testingtransmission and reception performance of a data packet signaltransceiver device under test (DUT) includes: receiving, with a DUT, atester data packet signal including a trigger frame and having a testertransmit output power (TTOP), wherein the trigger frame includes datacorresponding to a reported tester transmit power (RTTP) of the testerdata packet signal, wherein the RTTP and TTOP are unequal, and a desiredreceived signal strength (TRSS) of a DUT data packet signal to bereceived by a tester from the DUT; transmitting, with the DUT for thetester, a DUT data packet signal having a DUT transmit output power ofRTTP-DRSS+TRSS, wherein DRSS is a received signal strength of the testerdata packet signal reported by the DUT; and repeating the receiving andthe transmitting for a plurality of combinations of values of the TTOP,the RTTP and the DRSS.

In accordance with further exemplary embodiments, a method of testingtransmission and reception performance of a data packet signaltransceiver device under test (DUT) includes: transmitting, with atester, a tester data packet signal including a trigger frame and havinga tester transmit output power (TTOP), wherein the trigger frameincludes data corresponding to a reported tester transmit power (RTTP)of the tester data packet signal, wherein the RTTP and TTOP are unequal,and a desired received signal strength (TRSS) of a DUT data packetsignal to be received by the tester from a DUT; receiving, with the DUT,the tester data packet signal and in response thereto reporting areceived signal strength (DRSS) of the tester data packet signalreceived by the DUT; transmitting, with the DUT, a DUT data packetsignal having a DUT transmit output power of RTTP-DRSS+TRSS; receiving,with the tester, the DUT data packet signal; and repeating thetransmitting with the tester, the receiving with the DUT, thetransmitting with the DUT, and the receiving with the tester for aplurality of combinations of values of the TTOP, the RTTP and the DRSS.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a wired, or conductive, test environment for testing adata packet signal transceiver device in accordance with exemplaryembodiments.

FIG. 2 depicts a wireless, or radiative, test environment for testing adata packet signal transceiver device in accordance with exemplaryembodiments.

FIG. 3 depicts transmission by a DUT of multiple data packets havingpredetermined intended power levels for testing a data packet signaltransceiver device in accordance with exemplary embodiments.

FIG. 4 depicts a table of predetermined intended power levels andcorresponding received power levels for the data packets of FIG. 3.

FIG. 5 depicts an example sequence of data packet signal exchangesbetween a tester and DUT for testing a data packet signal transceiverdevice in accordance with exemplary embodiments.

FIG. 6 depicts comparative graphs of ideal and realistic availabletransmit power levels, minimum through maximum, from a DUT.

FIG. 6A depicts, qualitatively, multiple values of actual DUT outputpowers produced in response to corresponding intended, or programmed,DUT output powers in accordance with two example step size resolutions.

FIG. 7 depicts comparative graphs of ideal and realistic linearity ofreceived signal strength indication (RSSI) measurements by a DUT.

FIG. 8 depicts another example sequence of data packet signal exchangesbetween a tester and DUT for testing a data packet signal transceiverdevice in accordance with exemplary embodiments.

FIG. 9 depicts a table of intended power levels and actual power levelsfor the data packets of FIG. 8.

DETAILED DESCRIPTION

The following detailed description is of example embodiments of thepresently claimed invention with references to the accompanyingdrawings. Such description is intended to be illustrative and notlimiting with respect to the scope of the present invention. Suchembodiments are described in enough detail to enable one of ordinaryskill in the art to practice the subject invention, and it will beunderstood that other embodiments may be practiced with some variationswithout departing from the spirit or scope of the subject invention.

Throughout the present disclosure, absent a clear indication to thecontrary from the context, it will be understood that individual circuitelements as described may be singular or plural in number. For example,the terms “circuit” and “circuitry” may include either a singlecomponent or a plurality of components, which are either active and/orpassive and are connected or otherwise coupled together (e.g., as one ormore integrated circuit chips) to provide the described function.Additionally, the term “signal” may refer to one or more currents, oneor more voltages, or a data signal. Within the drawings, like or relatedelements will have like or related alpha, numeric or alphanumericdesignators. Further, while the present invention has been discussed inthe context of implementations using discrete electronic circuitry(preferably in the form of one or more integrated circuit chips), thefunctions of any part of such circuitry may alternatively be implementedusing one or more appropriately programmed processors, depending uponthe signal frequencies or data rates to be processed. Moreover, to theextent that the figures illustrate diagrams of the functional blocks ofvarious embodiments, the functional blocks are not necessarilyindicative of the division between hardware circuitry.

Wireless devices, such as cellphones, smartphones, tablets, etc., makeuse of standards-based technologies, such as IEEE 802.11a/b/g/n/ac(“WiFi”), 3GPP LTE, Bluetooth, Zigbee, Z-Wave, etc. The standards thatunderlie these technologies are designed to provide reliable wirelessconnectivity and/or communications. The standards prescribe physical andhigher-level specifications generally designed to be energy-efficientand to minimize interference among devices using the same or othertechnologies that are adjacent to or share the wireless spectrum.

Tests prescribed by these standards are meant to ensure that suchdevices are designed to conform to the standard-prescribedspecifications, and that manufactured devices continue to conform tothose prescribed specifications. Most devices are transceivers,containing at least one or more receivers and one or more transmitters.Thus, the tests are intended to confirm whether the receivers andtransmitters both conform. Tests of the receiver(s) of the DUT (RXtests) typically involve a test system (tester) sending test packets tothe receiver(s) and some way of determining how the DUT receiver(s)respond to those test packets. Tests of the transmitter(s) of the DUT(TX tests) are performed by having them send packets to the test system,which may then evaluate various physical characteristics of the signalsfrom the DUT.

Testing of wireless devices, such as Wi-Fi, Bluetooth, Zigbee and Z-Wavedevices, has progressed from frequent two-way messaging between a testerand DUT to infrequent messaging between which major portions of testflows are executed within and coordinated between tester and DUT usingnon-link test solutions where only the unique device identifier andportions of the PHY are active. However, results of such tests wouldtypically have been conveyed from DUT to tester via communications portsand pathways as the upper level of the protocol stack is not active,thereby preventing data from being easily conveyed in the transmittedpackets. Therefore, where the only connection between a DUT and testeris either conducted or radiated signal paths and the data exchanged isvia data packets, it may be difficult, if possible at all, for a DUT toconvey test results to a tester using non-link test methods. Asdiscussed in more detail below, in accordance with exemplary embodimentsof the presently claimed invention, testing of a RF data packettransceiver can be performed, at least in part, by testing at lowerlayers of the network data packet signal communications protocol.

Referring to FIG. 1, a typical testing environment 10 a includes atester 12 and a DUT 16, with test data packet signals 21 t and DUT datapacket signals 21 d exchanged as RF signals conveyed between the tester12 and DUT 16 via a conductive signal path 20 a, typically in the formof co-axial RF cable 20 c and RF signal connectors 20 tc, 20 dc. Asnoted above, the tester typically includes a signal source 14 g (e.g., aVSG) and a signal analyzer 14 a (e.g., a VSA). The tester 12 and DUT 16may also include preloaded information regarding predetermined testsequences, typically embodied in firmware 14 f within the tester 12 andfirmware 18 f within the DUT 16. The testing details within thisfirmware 14 f, 18 f about the predetermined test flows typically requiresome form of explicit synchronization between the tester 12 and DUT 16,typically via the data packet signals 21 t, 21 d.

Alternatively, testing may be controlled by a controller 30 which may beintegral to the tester 12 or external (e.g., a local or networkedprogrammed personal computer) as depicted here. The controller 30 maycommunicate with the DUT 16 via one or more signal paths (e.g., Ethernetcabling, network switches and/or routers, etc.) 31 d to convey commandsand data. If external to the tester 12, the controller 30 may furthercommunicate with the tester 12 via one or more additional signal paths(e.g., Ethernet cabling, network switches and/or routers, etc.) 31 t toconvey additional commands and data.

While the controller 30 and tester 12 are depicted as separate devicesor systems, references to a “tester” in the following discussion mayinclude separate devices or systems as depicted here and may alsoinclude a combined device or system in which the functions andcapabilities of the controller 30 and tester 12 described above may beco-located in a common hardware infrastructure. Accordingly, unlessotherwise specifically required or limited, references made to variouscontrol functions and/or commands may be considered to originate in atester 12, a controller 30 or a combined tester/controller system (notshown). Similarly, storage of commands, data, etc., may be considered tobe done in a tester 12, a controller 30 or a combined tester/controllersystem, or alternatively in memory devices located remotely via anetwork as noted above.

Referring to FIG. 2, an alternative testing environment 10 b uses awireless signal path 20 b via which the test data packet signals 21 tand DUT data packet signals 21 d may be communicated via respectiveantenna systems 20 ta, 20 da of the tester 12 and DUT 16.

As discussed in more detail below, a trigger based test (TBT) may beadvantageously used in which a tester sends a data packet containing atrigger frame to the DUT, thereby causing the DUT to timely reply with afrequency corrected signal. As is well known in the art, in conformancewith the IEEE 802.11 set of specifications, a trigger frame may beprovided by an access point (AP, e.g., a tester in a test environment)for a STA device (e.g., a DUT in the test environment) and includevarious types of information about the transmitted signal from thetester emulating an AP access point. For example, the actual signalpower transmitted by the tester (e.g., via its VSG) may be controlledseparately from the reported tester power level information contained inthe trigger frame, and thereby emulate a path loss does not exist. Also,desired RSSI information may be contained in the trigger frameidentifying the strength of the data packet signal to be sent in replyby the DUT. The DUT may calculate a path loss as the difference in powerbetween the reported transmitted power by the tester and the DUTreceived signal strength, and then calculate a transmit power as thedesired RSSI (at the tester) plus the calculated path loss.

However, the transmit power as measured by the tester is affected by twoerrors: a difference between the intended and actual transmit powers,and RSSI measurement error. As discussed in more detail below, this maybe compensated by “forcing” transmissions of multiple TX powerssupported by the DUT prior to the TBT test. By using MPS, the intendedTX power may be known a priori for each DUT TX power chosen fortransmission and associated with a corresponding actual received TXpower as measured at the tester. This may then be followed bytraditional TBT testing, and from the measured transmit power theintended power level chosen by the DUT may be determined, therebyenabling a calculation of the RSSI (at the DUT) the DUT must have usedto select the chosen intended transmit power. This enables adetermination (e.g., inferential) of the DUT RSSI without querying theDUT. This may be further extended by repeating the TBT step fordifferent RSSI levels in the DUT and then sweeping the RSSI level duringverification.

For example, the TX power of a DUT may be scanned and measured for aknown number of transmit power levels (e.g., using MPS), followed by aTBT test for the different RSSI levels to be tested, during which thetarget power level may remain fixed or it may be varied. Maintaining afixed target power (power of DUT TX signal as received by tester)enables reuse of a test data packet (e.g., by varying the VSG outputpower level, thereby effectively modelling a different path loss as seenby the DUT), though it may limit the power range within the DUT whensweeping a large RSSI range. As noted, once the TX power level selectedby the DUT has been identified, the corresponding RSSI within the DUTmay be calculated. Alternatively, a constant VSG output power may bemaintained while transmitting different trigger frames packets (e.g.,with modified reported VSG output powers and target tester RSSI levels).

Referring to FIGS. 3 and 4, a sequence 102 of multiple data packetsignals (e.g., each having single or multiple data packets as desired orneeded) having predetermined intended power levels 102 i may betransmitted by the DUT and received by the tester to determine thecorresponding actual power levels 102 r for each transmission. Forexample, MPS may first be used to determine the DUT TX power as measuredby the tester (e.g., at the VSA) for a given TX power setting within theDUT. This may be advantageous to validate the DUT TX power accuracy. TheDUT may, as desired or needed, transmit a single data packet or multipledata packets (the number of which will typically be known a priori),e.g., beginning with a first power TX10 (10 dbm), followed by one ormore similar data packet transmissions, e.g., TX11, TX12, . . . , TX20.(For purposed of this example, TX10, TX11, TX12, . . . , TX20 indicateintended power levels 102 i of +10 dBm, +11 dBm, +12 dBm, . . . , +20dBm, respectively, though other power ranges may be used as desired orneeded.)

The tester (e.g., the VSA) measures the received power 102 r of eachtransmitted signal and creates a table of the respective correspondingintended 102 i and received 102 r (e.g., as measured by the VSA) powerlevels as shown. For example, while the DUT TX signal was intended(e.g., by design of the DUT transmitter circuitry) to be 15 dBm, the VSAmay measure the actual received power as 14.5 dBm. These correspondingvalues may be stored in memory (e.g., locally within the tester orremotely within memory accessible via a network) for later use (asdiscussed below). The DUT may then be programmed for operating in a TBTmode.

Referring to FIG. 5, examples of tester data packet signal sequences 202t and DUT data packet signal sequences 202 d may be exchanged as shown.These examples demonstrate how different settings may be used toindirectly control DUT TX power to be a constant 15 dBm. Other levelsand combination of levels may be used as desired or needed. In anyevent, it may be desirable to keep one parameter constant to enabledetection of other factors (e.g., thermal changes etc.) affectingperformance characteristics.

In a first tester sequence 203 ta the tester may transmit a data packetsignal at a tester transmit output power TTOP of −40 dBm with a triggerframe containing data identifying a reported tester transmit power RTTPof +10 dBm, and data identifying a desired, or expected, received signalstrength TRSS of −35 dBm for the DUT data packet signal to be receivedby the tester. In the first DUT sequence 203 da the DUT determines itsreceived signal strength DRSS to be −40 dBm and calculates a perceivedpath loss PPL as follows:

PPL=RTTP−DRSS=+10 dBm−(−40 dBm)=50 dB

Hence, with a 50 dB path loss and a desired RSSI at the tester (afteraccounting for path loss) of −35 dBm the DUT must transmit an intendedDUT transmit power IDTP as follows:

IDTP=TRSS+PPL=−35 dBm+50 dB=+15 dBm

The tester captures the response data packet signal from the DUT with areceived power of +14.4 dBm and compares this with its correspondingIDTP of +15 dBm (FIG. 4). Accordingly, as this was what was expected,the RSSI determined by the DUT is considered as accurate.

In the next tester sequence 203 tb, the tester may transmit a datapacket signal at a tester transmit output power TTOP of −42 dBm with atrigger frame containing data identifying a reported tester transmitpower RTTP of +8 dBm (e.g., versus the previous TTOP of +10 dBm), anddata identifying the same desired, or expected, received signal strengthTRSS of −35 dBm for the DUT data packet signal to be received by thetester. In the responsive DUT sequence 203 db the DUT determines itsreceived signal strength DRSS to be −42 dBm and calculates a perceivedpath loss PPL as follows:

PPL=RTTP−DRSS=+8 dBm−(−42 dBm)=50 dB

Hence, with a 50 dB path loss and a desired RSSI at the tester (afteraccounting for path loss) of −35 dBm the DUT must again transmit anintended DUT transmit power IDTP of +15 dBm. Accordingly, the testercaptures the response data packet signal from the DUT with a receivedpower of +14.4 dBm and compares this with its corresponding IDTP of +15dBm (FIG. 4). Again, as this was what was expected, the RSSI determinedby the DUT is considered as accurate.

In the third tester sequence 203 tc, the tester may transmit a datapacket signal at a tester transmit output power TTOP of −44 dBm with atrigger frame containing data identifying a reported tester transmitpower RTTP of +10 dBm (e.g., as in the first sequence 203 ta), and dataidentifying the same desired, or expected, received signal strength TRSSof −39 dBm for the DUT data packet signal to be received by the tester.In the responsive DUT sequence 203 dc the DUT determines its receivedsignal strength DRSS to be −44 dBm and calculates a perceived path lossPPL as follows:

PPL=RTTP−DRSS=+10 dBm−(−44 dBm)=54 dB

Hence, with a 54 dB path loss and a desired RSSI at the tester (afteraccounting for path loss) of −39 dBm the DUT must again transmit anintended DUT transmit power IDTP of +15 dBm. Accordingly, the testercaptures the response data packet signal from the DUT with a receivedpower of +14.4 dBm and compares this with its corresponding IDTP of +15dBm (FIG. 4). Again, as this was what was expected, the RSSI determinedby the DUT is considered as accurate.

In the last tester sequence 203 td, an erroneous DUT received signalstrength DRSS may be detected. For example, the tester may transmit adata packet signal at a tester transmit output power TTOP of −38 dBmwith a trigger frame containing data identifying a reported testertransmit power RTTP of +10 dBm, and data identifying the same desired,or expected, received signal strength TRSS of −33 dBm for the DUT datapacket signal to be received by the tester. In the responsive DUTsequence 203 dc the DUT determines its received signal strength DRSS tobe −39 dBm (versus the −38 dBm that was transmitted) and calculates aperceived path loss PPL as follows:

PPL=RTTP−DRSS=+10 dBm−(−39 dBm)=49 dB

Hence, with a 49 dB path loss and a desired RSSI at the tester (afteraccounting for path loss) of −33 dBm the DUT must transmit an intendedDUT transmit power IDTP as follows:

IDTP=TRSS+PPL=−33 dBm+49 dB=+16 dBm

The tester captures the response data packet signal from the DUT with areceived power of +15.5 dBm and compares this with its correspondingIDTP of +16 dBm (FIG. 4). Accordingly, as this was not what wasexpected, the RSSI determined by the DUT is considered as erroneous.

As will be readily understood by one skilled in the art, many variationsof this process may be practiced, e.g., for various combinations ofvalues of TTOP, RTTP and TRSS. For example, while the DUT TX power neednot necessarily remain constant, keeping it constant may advantageouslyenable tracking of first order effects such as temperature andtemperature compensation mechanisms (e.g., the DUT may be designed toincrease its TX power if it is detected as having decreased due toincreased temperature).

Referring to FIG. 6, while a DUT may be designed to provide certaintransmit signal performance characteristics 302 i, its actualperformance characteristics 302 r often vary. For example, while a DUTmay be designed to ideally provide transmit power levels over a linearrange 303 ic, from a minimum power 303 ia through a maximum power 303ib, its realistic transmit power levels may be provided instead over anon-linear range 303 ir, with a different minimum power 303 ir andmaximum power 303 ir.

Referring to FIG. 6A, as will be readily appreciated, depending upon thespecific power levels 307, 309 specified by the tester for production bythe DUT, it may be desirable for a larger number of power levels to bespecified and measured during testing. Hence, to ensure that the minimum303 a and maximum 303 b actual power levels are accurately determined,e.g., at the power levels 307 b, 307 f where power become constant as ittransitions from a variable power 303 c to the minimum 303 a or maximum303 b power, it may be desirable to specify a larger number of powersteps. For example, it may be preferable to use smaller input power stepintervals 303 cib that result in corresponding output power stepintervals 303 cob (as indicated with “squares”) that not only identifythe power levels 307 b, 307 f at which the minimum 303 a and maximum 303b output power levels initially occur but also identify the power levels307 a, 307 g beyond at which the minimum 303 a and maximum 303 b outputpower levels remain constant. In contrast thereto, if larger input powerstep intervals 303 cia are used, the correspondingly larger output powerstep intervals 303 coa (as indicated with “circles”) may result infailures to capture the transition power levels 307 b, 307 f at whichthe minimum 303 a and maximum 303 b output power levels initially occur.

Referring to FIG. 7, similarly, while a DUT may be designed to providecertain receive signal performance characteristics, its actualperformance characteristics will often vary. For example, while a DUTmay be designed to ideally determine received signal strengths 305 ilinearly over the range of expected received signals 303 ic, itsrealistic measured received signal strengths 305 r may exhibitnon-linear variances.

In accordance with further exemplary embodiments, a trigger based test(TBT) may be used to enable information presented to a DUT to controlits behavior and allow extraction of parameters needed to perform acalibration (e.g., a form of trim calibration, since an initial defaultcalibration will have generally been performed during design and earliermanufacturing processes). As part of the TBT the packet sent to the DUTmay include information about the data packet transmit power (e.g., fromthe tester), and the desired RSSI (at the tester). The DUT may use thisto determine the path loss between the source of the data packet (thetester) and the DUT (path loss=transmitted power of data packet−RSSI atDUT), with which the DUT may select the appropriate DUT TX power to getthe desired RSSI at the data packet source (DUT TX power=testerRSSI+path loss). Using a tester as the source enables significantcontrol. For example, simply controlling the input power to the DUT witha given data packet enables control of the DUT TX power. For example, ifthe same data packet is sent to a DUT at two different tester transmitpower levels, the DUT should estimate two different path lossesconsistent with the difference between the two tester transmit powerlevels, and since the data packet is identical, the resulting DUT TXpower levels should ideally be the difference between the two sent datapackets. Similarly, the actual tester transmit power may be maintainedconstant while changing the desired RSSI at the tester and/or thereported tester transmit power and thereby cause the DUT to transmit ata different TX power.

With these techniques the linearity of DUT transmit power may bemeasured by keeping RSSI constant to the DUT (e.g., by using a constanttransmit power from the tester) and control the data packet contents tocause the DUT to transmit at different power levels, thereby effectivelysweeping the power control range. Assuming the supported power range isknown (e.g., the DUT limits its minimum and maximum power levels), thelevel may be determined where the DUT ceases to correct its transmitpower, thereby revealing its internal TX value and essentially make theswept curve absolute. Then, with the RSSI level used known as well, andthe TX power step used is known, the RSSI measured by the DUT may bedetermined. This then further enables sweeping the RSSI input levels tothe DUT, ideally keeping the DUT TX power constant by controlling thedata packet contents to force the DUT to transmit the same power levelfor a given RSSI provided into the DUT. Additionally, the RSSI may bestepped in increments finer than the capabilities of the DUT RSSI levelreporting to determine where the switch over point is. Performing a fullRSSI sweep will enable correction of the actual RSSI curve based onoffsets from the expected (“ideal”) RSSI curve.

Referring to FIGS. 8 and 9, other examples of tester data packet signalsequences 402 t and DUT data packet signal sequences 402 d (e.g., witheach signal 402 t, 402 d having single or multiple data packets asdesired or needed) may be exchanged, with predetermined intended powerlevels 402 di transmitted by the DUT and received by the tester todetermine the corresponding actual power levels 402 dr for eachtransmission. For example, once a table of corresponding intended andactual DUT TX power levels (e.g., similar to FIG. 4) is determined, asimilar determination of corresponding RSSI values may be made. (Thisexample picks up near the end of a power sweep so similar measurementsmay be performed prior to reaching this point in the test.).

In a first tester sequence 403 ta, with a target DUT TX power of +17dBm, the tester may transmit a data packet signal at a tester transmitoutput power TTOP of −40 dBm with a trigger frame containing dataidentifying a reported tester transmit power RTTP of +10 dBm, and dataidentifying a desired, or expected, received signal strength TRSS of −33dBm for the DUT data packet signal to be received by the tester. In thefirst DUT sequence 403 da the DUT erroneously determines its receivedsignal strength DRSS to be −41 dBm and calculates a perceived path lossPPL as follows:

PPL=RTTP−DRSS=+10 dBm−(−41 dBm)=51 dB

Hence, with an erroneous 51 dB path loss and a desired RSSI at thetester (after accounting for path loss) of −33 dBm the DUT must transmitan intended DUT transmit power IDTP as follows:

IDTP=TRSS+PPL=−33 dBm+51 dB=+18 dBm

The tester (e.g., the VSA) captures the response data packet signal fromthe DUT with a received power of +19.0 dBm but it cannot be determinedif the DUT TX power is off by 2 dB, or if the RSSI is off by 2 dB, or ifboth are off by some other combination (e.g., each is off by 1 dB).

In the next tester sequence 403 tb, with a target DUT TX power of +18dBm, the tester maintains a constant tester transmit output power TTOPof −40 dBm with a trigger frame containing data identifying a constantreported tester transmit power RTTP of +10 dBm, and data identifying anincreased desired, or expected, received signal strength TRSS of −32 dBmfor the DUT data packet signal to be received by the tester. In theresponsive DUT sequence 403 db the DUT again erroneously determines itsreceived signal strength DRSS to be −41 dBm and again erroneouslycalculates a perceived path loss PPL of 51 dB. Accordingly, the DUTdetermines it must transmit an intended DUT transmit power IDTP asfollows:

IDTP=TRSS+PPL=−32 dBm+51 dB=+19 dBm

The tester captures the response data packet signal from the DUT with areceived power of +20.0 dBm but, again, the source(s) of the error is(are) unknown.

In the third tester sequence 403 tc, with a target DUT TX power of +18dBm, the tester maintains a constant tester transmit output power TTOPof −40 dBm with a trigger frame containing data identifying a constantreported tester transmit power RTTP of +10 dBm, and data identifying afurther increased desired, or expected, received signal strength TRSS of−31 dBm for the DUT data packet signal to be received by the tester. Inthe responsive DUT sequence 403 dc the DUT again erroneously determinesits received signal strength DRSS to be −41 dBm and again erroneouslycalculates a perceived path loss PPL of 51 dB. Accordingly, the DUTdetermines it must transmit an intended DUT transmit power IDTP asfollows:

IDTP=TRSS+PPL=−31 dBm+51 dB=+20 dBm

The tester captures the response data packet signal from the DUT with areceived power of +20.8 dBm.

In the next tester sequence 403 td, the tester maintains a constanttester transmit output power TTOP of −40 dBm with a trigger framecontaining data identifying a constant reported tester transmit powerRTTP of +10 dBm, and data identifying a further increased desired, orexpected, received signal strength TRSS of −30 dBm for the DUT datapacket signal to be received by the tester. In the responsive DUTsequence 403 dd the DUT again erroneously determines its received signalstrength DRSS to be −41 dBm and again erroneously calculates a perceivedpath loss PPL of 51 dB. Accordingly, the DUT determines it must transmitan intended DUT transmit power IDTP as follows:

IDTP=TRSS+PPL=−30 dBm+51 dB=+21 dBm

The tester again captures the response data packet signal from the DUTwith a received power of +20.8 dBm.

In the last tester sequence 403 te, with an increased target DUT TXpower of +20 dBm, the tester maintains a constant tester transmit outputpower TTOP of −40 dBm with a trigger frame containing data identifying aconstant reported tester transmit power RTTP of +10 dBm, and dataidentifying a further increased desired received signal strength TRSS of−29 dBm for the DUT data packet signal to be received by the tester. Inthe responsive DUT sequence 403 de the DUT again erroneously determinesits received signal strength DRSS to be −41 dBm and again erroneouslycalculates a perceived path loss PPL of 51 dB. Accordingly, the DUTdetermines it must transmit an intended DUT transmit power IDTP asfollows:

IDTP=TRSS+PPL=−29 dBm+51 dB=+22 dBm

The tester again captures the response data packet signal from the DUTwith a received power of +20.8 dBm.

However, as it is known that the DUT TX power is limited to a maximum of+20 dBm, it may be concluded that, with the TRSS of −31 dBm resulting in+20 dBm being transmitted by the DUT, the DRSS is off by 1 dB, since theDUT is transmitting +20 dBm and must be doing so as a result of the DUTerroneously calculating a path loss of 51 dB to decide on the +20 dBmDUT TX power. Accordingly, a table (FIG. 9) of corresponding intended402 di and received 402 dr DUT TX powers may be derived.

Various other modifications and alternatives in the structure and methodof operation of this invention will be apparent to those skilled in theart without departing from the scope and the spirit of the invention.Although the invention has been described in connection with specificpreferred embodiments, it should be understood that the invention asclaimed should not be unduly limited to such specific embodiments. It isintended that the following claims define the scope of the presentinvention and that structures and methods within the scope of theseclaims and their equivalents be covered thereby.

What is claimed is:
 1. A method of testing transmission and receptionperformance of a data packet signal transceiver device under test (DUT),comprising: transmitting, with a tester for a DUT, a tester data packetsignal including a trigger frame and having a tester transmit outputpower (TTOP), wherein said trigger frame includes data corresponding toa reported tester transmit power (RTTP) of said tester data packetsignal, wherein said RTTP and said TTOP are unequal, and a desiredreceived signal strength (TRSS) of a DUT data packet signal to bereceived by said tester from said DUT; receiving, with said tester fromsaid DUT, a DUT data packet signal having a DUT transmit output power ofRTTP-DRSS+TRSS, wherein DRSS is a received signal strength of saidtester data packet signal reported by said DUT; and repeating saidtransmitting and said receiving for a plurality of combinations ofvalues of said TTOP, said RTTP and said DRSS.
 2. The method of claim 1,wherein said RTTP is greater than said TTOP.
 3. The method of claim 1,wherein said repeating of said transmitting and said receiving comprisessuccessively increasing said TRSS at least until said received signalstrength of the DUT data packet signal received by said tester from saidDUT remains constant.
 4. The method of claim 1, wherein said repeatingof said transmitting and said receiving comprises successivelydecreasing said TRSS at least until said received signal strength ofsaid DUT data packet signal received by said tester from said DUTremains constant.
 5. A method of testing transmission and receptionperformance of a data packet signal transceiver device under test (DUT),comprising: receiving, with a DUT, a tester data packet signal includinga trigger frame and having a tester transmit output power (TTOP),wherein said trigger frame includes data corresponding to a reportedtester transmit power (RTTP) of said tester data packet signal, whereinsaid RTTP and said TTOP are unequal, and a desired received signalstrength (TRSS) of a DUT data packet signal to be received by a testerfrom said DUT; transmitting, with said DUT for said tester, a DUT datapacket signal having a DUT transmit output power of RTTP-DRSS+TRSS,wherein DRSS is a received signal strength of said tester data packetsignal reported by said DUT; and repeating said receiving and saidtransmitting for a plurality of combinations of values of said TTOP,said RTTP and said DRSS.
 6. The method of claim 5, wherein said RTTP isgreater than said TTOP.
 7. The method of claim 5, wherein said repeatingof said receiving and said transmitting comprises successivelyincreasing said TRSS at least until said received signal strength of theDUT data packet signal remains constant.
 8. The method of claim 5,wherein said repeating of said receiving and said transmitting comprisessuccessively decreasing said TRSS at least until said received signalstrength of said DUT data packet signal remains constant.
 9. A method oftesting transmission and reception performance of a data packet signaltransceiver device under test (DUT), comprising: transmitting, with atester, a tester data packet signal including a trigger frame and havinga tester transmit output power (TTOP), wherein said trigger frameincludes data corresponding to a reported tester transmit power (RTTP)of said tester data packet signal, wherein said RTTP and said TTOP areunequal, and a desired received signal strength (TRSS) of a DUT datapacket signal to be received by said tester from a DUT; receiving, withsaid DUT, said tester data packet signal and in response theretoreporting a received signal strength (DRSS) of said tester data packetsignal received by said DUT; transmitting, with said DUT, a DUT datapacket signal having a DUT transmit output power of RTTP-DRSS+TRSS;receiving, with said tester, said DUT data packet signal; and repeatingsaid transmitting with said tester, said receiving with said DUT, saidtransmitting with said DUT, and said receiving with said tester for aplurality of combinations of values of said TTOP, said RTTP and saidDRSS.
 10. The method of claim 9, wherein said RTTP is greater than saidTTOP.
 11. The method of claim 9, wherein said repeating saidtransmitting with said tester, said receiving with said DUT, saidtransmitting with said DUT, and said receiving with said testercomprises successively increasing said TRSS at least until said receivedsignal strength of the DUT data packet signal received by said testerremains constant.
 12. The method of claim 1, wherein said repeating saidtransmitting with said tester, said receiving with said DUT, saidtransmitting with said DUT, and said receiving with said testercomprises successively decreasing said TRSS at least until said receivedsignal strength of said DUT data packet signal received by said testerremains constant.